Watch: 'Death to America, Israel' chants echo as Ayatollah Ali Khamenei's funeral begins

Thousands of mourners filled Tehran's Grand Mosalla on Saturday, chanting "Death to America" and "death to Israel" as the public funeral ceremonies for Iran's late Supreme Leader Ayatollah Ali Khamenei began. Red banners, symbolizing calls for revenge, were carried by attendees at the vast religious complex, where Iranian authorities anticipate 15 to 20 million people will participate over three days.

Khamenei, who led the Islamic Republic from 1989 until his death at age 86, will be mourned throughout a week-long farewell. His coffin will lie in state until Monday, followed by processions through Tehran, Qom, and then to the Iraqi Shia holy cities of Baghdad, Karbala, and Najaf. The final burial is scheduled for Thursday in Mashhad.

The funeral proceedings are under heavy security, expected to be the largest public gathering in Iran since the 1989 funeral of Ayatollah Ruhollah Khomeini. Authorities have implemented road closures, airspace restrictions, and stationed water tankers due to forecasts of temperatures exceeding 35 degrees Celsius (95 degrees Fahrenheit).

Senior Iranian leaders, including Parliament Speaker Mohammad Bagher Ghalibaf, attended the opening ceremony. International dignitaries present included Pakistan Prime Minister Shehbaz Sharif and Russian Security Council Deputy Chairman Dmitry Medvedev. Representatives from Hamas, Hezbollah, and Afghanistan's Taliban government were also in attendance. Observers are particularly watching for any public appearance by Mojtaba Khamenei, the late leader's son and designated successor, who has not been seen publicly since his father's death.